1. Technical Field
This invention relates to a device for holding a flap door to a horizontal position so that, when opened, it may be kept flat on the top wall of a hollow body such as a cabinet to which the flap door is fitted in order to maximize the open space available to the user.
2. Prior Art
A flap door provided with a damper is advantageous in that the action of closing the door is carried out without impact, because once the door is pulled forward, the damper reduces the torque generated by the dead weight of the door and brakes any sudden movement of the door so that the latter may be closed softly without giving out any shock.
A flap door having a damper of the above identified type is, however, not without defect, because, if it is turned upward to a horizontal position by hand and then left out of the hand, the door can unintentionally be turned downward to the closed position by its own dead weight and, if the flap door is on the way to the closed position from a position when it is held back on the top wall of hollow body such as a cabinet to which is is fitted and has been moved forward by more than a half of its height, in other words, if the center of gravity of the flap door has passed the axis of rotation of the damper, when the hand holding it is pulled away from it, leaving the door to turn further by itself, the door can abruptly fling forward and downward to a great danger of the user as it is turned downward by the torque generated by its own dead weight.
In an attempt to avoid this particular problem, an improved flap door having a damper has been proposed by the applicant of the present application, said improvement consisting in keeping the door open at a horizontal position under a locked condition when it is turned open from the closed vertical position so that it may not unintentionally turn back to the closed position, if the hand holding it is pulled away from it and also it may not unintentionally fling forward if the hand holding it is pulled away from it if the hand holding it is pulled away from it if it is turned forward and downward from a position where it is held on the top wall of a hollow body such as a cabinet to which it is fitted all the way to the closed vertical position.
FIG. 9 of the accompanying drawings schematically shows a side view of an embodiment of an improved flap door proposed by the applicant of the present application. Referring to FIG. 9, a hollow body a such as a cabinet to which the embodiment of a flap door 1 is fitted has a cut-out section b. A bracket c is fitted to the cut-out section b, said bracket c comprising a bottom plate and a pair of lateral plates h, h. Said bottom plate f has a recess e cut along a side thereof and a groove g having an opening connected to the recess e. Said lateral plates h, h have horizontal slots j, j for slidably holding a lock pin i extending between the lateral plates h, h at the opposite ends thereof. A spring k is disposed in said groove g to urge the lock pin forward such that, in the open horizontal position of the door l, the lock pin i engages a notch n arranged on the outer periphery of the outer sleeve m of the damper d of the embodiment to hold the door l to the open horizontal position.
With a flap door having a damper according to the previous invention of the applicant of the present application and having a configuration as described above, since the slots j, j for slidably holding the lock pin i is straight and extends horizontally, the spring k is deformed to a great extent when the lock pin i is released from its locked condition, although not so remarkably when the door l is held horizontal and the lock pin i is engaged with the notch n. Therefore, under the released condition of the lock pin i, undesirably large force is required to open the flap door, because of the friction between the lock pin i and the outer peripheral surface of the outer sleeve m of the damper d, if the door l is not supposed to require such large force for opening once the lock pin i is released. Additionally, the outer sleeve m and the lock pin i also show large friction otherwise and can be worn out in a relatively short period of time.
In view of the above described and other problems of the prior art, it is an object of the present invention to provide a device for holding a flap door to a horizontal position by arranging a pair of curved roller pin receiving slots having a given radius of curvature in the device so that a roller pin which is slidably received by said slots is unlocked as the flap door is turned from the open horizontal position to the closed vertical position without applying large pressure on the outer peripheral surface of the outer sleeve of a damper if the spring that urges the roller pin is deformed to a great extent and consequently there may not arise any undesired load when the door is being opened while the friction between the roller pin and the outer peripheral surface of the outer sleeve of the damper and hence the wear of these components may be minimized to prolong the service life of the flap door by arranging the roller pin to rotate along the outer peripheral surface of the outer sleeve of the damper as the roller pin is strongly urged by the heavily deformed spring.
Another object of the present invention is to provide a device for holding a flap door to a horizontal position by an arrangement substantially the same as described above, wherein the roller pin is not received by a pair of curved slots but supported by a pair of links connected to the opposite ends of the roller pin in order to bring forth a similar effect.